It has been estimated that about 45% of the U. S. population seeks medical help for pain. Chronic pain can result from various disease conditions such as diabetes, rheumatoid arthritis, lower back pain, cancer, MS and HIV. The available therapeutic options for the treatment of chronic pain are inadequate. Therefore novel drug strategies are needed to treat this chronic condition. A promising drug target for treatment of inflammation and pain is the cannabinoid CB2 receptor. Our goal is to develop a high efficacy CB2 receptor agonist, because such agonists are likely to reduce pain, with fewer side effects than nonselective cannabinoids that also activate CB1 receptors. The specific aim of this proposal is to develop a CB2 agonist with good potency, efficacy and selectivity with respect to CB1 by structural optimization of our novel THC/anandamide hybrid template. We plan on developing a pharmacophore based on our SAR results which could then be used to design more active analogs. In order to distinguish between agonist and antagonist activity, analogs which bind effectively to the CB2 receptor will be evaluated for their ability to stimulate [35S]GTP3S binding. Compounds with high receptor affinity and which are active in stimulating [35S]GTP3S binding will then be tested for activity in the mouse tetrad model. Analogs that show little activity in the mouse tetrad model will then be evaluated in the LPS model followed by the formalin model and CCI model. The long term goal of this proposal is to develop a selective and potent CB2 agonist with pain suppression potential which could then be used as a lead in the development of a drug for the treatment of chronic pain. PUBLIC HEALTH RELEVANCE: CB2 receptor is an attractive target for the design of medication to treat inflammation and chronic pain. The long-term goal of this proposal is to develop a medication for the treatment of chronic pain conditions without undesirable CNS side effects.